The invention relates to a spinning machine having a plurality of spinning units for producing packages used as feeding packages for twisting. Each spinning unit has two drafting units, two false-twisting devices, a withdrawal device for two prestrengthened yarn components, which are guided together as a double yarn, and a device for winding the double yarn onto a yarn package. Devices are also provided for monitoring the quality with respect to a quality value combined from both yarn components, for interrupting the spinning operation when a quality defect is detected, and for holding ready a yarn end connected with a stopped partially wound spool package in a given position.
A spinning machine is known having a plurality of spinning units from German Examined Published patent application, (DE-A) 36 10 110, in which the prestrengthened yarn components, which were guided together to form a double yarn, pass through a quality monitor in order to be able to carry out a cleaning operation for the removal of unacceptably thick or thin points before the yarn components are wound onto the yarn package. As a criterion for the necessity of a cleaning, an overall yarn value is determined from both yarn components. If a quality defect is detected, both yarn components are separated, and the spinning operation is interrupted. In this construction, the end of the separated yarns moves onto the partially wound spool package.
It is also known from German Published Examined patent application (DE-A) 36 11 050, to lift the partially wound spool off its drive and to interrupt the spinning operation with a time delay when a quality defect is detected. The yarn or double yarn, which is continuously furnished while the partially wound spool package is being stopped, is sucked into a suction pipe. In the case of this construction, the yarn end, which is connected with the partially wound spool package, is available at a certain point for the piecing operation, at which it is held by means of a yarn clamp.
An object of the invention is to develop a spinning machine of the initially mentioned tYpe such that it is ensured, in a simple but nevertheless reliable manner, that the yarn is held ready at a defined point for a piecing operation, so that particularly no awkward searching is required for the yarn end or even two yarn ends on the partially wound spool package.
This object is achieved according to preferred embodiments of the invention in that, a program control unit is provided for the coordination of the time of the interruption of the spinning operation and the time of the stopping of the partially wound spool package.
It is therefore ensured that, on the one hand, no excessive quantity of fiber material is wasted, while, on the other hand, the yarn is not stressed by an untimelY clamping-fast or the like, in such a manner that it also breaks.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.